Luck Domain

You can touch a willing creature as a standard action, giving it a bit of luck. For the next round, any time the target rolls a d20, he may roll twice and take the more favorable result. You can use this ability a number of times per day equal to 3 + your Wisdom modifier.

At 6th level, as an immediate action, you can reroll any one d20 roll that you have just made before the results of the roll are revealed. You must take the result of the reroll, even if it's worse than the original roll. You can use this ability once per day at 6th level, and one additional time per day for every six cleric levels beyond 6th.